This Renewal Application for NRSA T32 MH20031 seeks to continue a highly successful Pre- and Post- Doctoral Fellowship Training Program (established in 1999) in HIV prevention research at Yale University's Center for Interdisciplinary Research on AIDS (CIRA). Over the past fourteen years we have successfully trained Post-Doctoral Fellows, with younger, early-career scientists thriving in our Pre-Doctoral Training component over the past nine years. CIRA, housed within the Yale School of Public Health at Yale University, provides an exceptional training environment that continues to keep step with the changing HIV/AIDS pandemic. Our training program is unique in providing the following combination of perspectives: a focus on vulnerable and underserved populations~ a strong foundation of training that emphasizes methodological rigor in both quantitative and qualitative analyses~ opportunities to conduct ethically sound, community based research, domestically and internationally~ and implementation science skills and methods to support the design and evaluation of interventions that are tailored to local contexts and study populations. We are requesting continued support for 3 Pre-Doctoral and 6 Post-Doctoral slots per year. The focus of both the Pre- and Post-Doctoral Fellowship is hands on conduct of research, analysis, paper and grant writing with a faculty mentor. All of our fellows are required to participate in a weekly seminar and lecture series. In addition, the Pre-Doctoral training also includes: formal course work, research preceptorship, seminars, outside courses and meetings, qualifying examinations, and dissertation research. Our approach to training future scientists for careers in HIV prevention research will emphasize flexibility and individual tailoring of Fellows' research preceptorships, while recognizing the importance of core training in methodology and the responsible conduct of research. Over the past 14 years we have successfully trained, and continue to train, 44 Post-Doctoral Fellows and 9 Pre-Doctoral fellows from a variety of disciplines. Fellows are both exposed to, and actively collaborate in, a wide array of studies and career trajectories, with an unprecedented opportunity to publish their own research. We are, therefore, confident in our ability to prepare both Pre- and Post-Doctoral Fellows with the strongest foundation of knowledge, skills, and experience to achieve and sustain careers as scientific investigators, contributing to advances in HIV prevention, specifically, and public health, in general.